Number distributions of T_dust of HMSCs. Three panels from bottom to top: number distributions in the distance ranges of <4 kpc, 4–8 kpc, and >8 kpc, respectively. The red, dark brown, and blue histograms represent the number distributions for S-type AS, O-type AS, and NA, respectively. The solid lines indicate their median values. The pink, brown, and cyan filled color regions have a full width of double standard deviation 2σ and center at median value of corresponding types of HMSCs.